OK. After much reading, I think I'm going to go with the TriTrix (I see what you mean; I was thinking of the cabinet as TriTrix, and the speakers as the RD).

However, I was wondering about something. If, in the future, I decide that I would like to add a larger woofers (or two), as you did, would it be as simple as adding another hole in the tower, and getting a separate crossover to control the new woofers, or would I have to completely redo the crossover to take the new speakers into account?

Also, is there any problem running a combination of 4 ohm and 8 ohm speakers off of my receiver, which is able to deliver around 90W at 6ohms? I understand the general idea of impedance, but I'm not sure how it all plays out.